Because of the great effort involved in writing two full-length novels every month, several guest writers were hired to write occasional installments in order to lighten Gibson's workload. These guest writers included Lester Dent , who also wrote the Doc Savage stories, and Theodore Tinsley . In the late 1940s, mystery novelist Bruce Elliott (also a magician) would temporarily replace Gibson as the primary author of the pulp series. [8] Richard Wormser , a reader for Street & Smith, wrote two Shadow stories. [9]